Manufacture of aliphatic alcohol



Oct. 26, 1937.

B. T. BROOKS 2,096,879

MANUFACTURE OF ALIPHATIC ALQOHOLS Filed Oct. 9, 1934 VA c 00', 377:. z.

m TER INLET HYDROLYZER of diethylsulfate is formed. The acid reaction Patented Oct. 26, 1931 y 2,096,879

UNITED STATES4PATENT. OFFICE MANUFACTURE OF AIJPHATIC ALCOHOL Benjamin T. Brooks, 01d Greenwich, Coma, as-

signor to Standard Alcohol Co;

Application October 9, 1234', Serial No. 147,509

i This invention relates to improvements in the repeated, as desired. It is, of course, necessary manufacture of alcohols and relates particularly to keep the process in operation, to add fresh to the manufacture of ethylalcohol from ethylsulfuric acid to the residual acid mixture to reene. place the acid removed as the ester, diethyl sul- In the manufacture of ethyl alcohol from fate. The net result of this operation is to pro- 5 ethylene by reacting upon ethylene with sulfuric duce ethyl alcohol with the minimum of sulacid, it is economically very important to produce furic acid, the direct absorption of 2' mole of the largest possible proportion of ethyl alcohol ethylene to one of surfuric acid being practically with the use .of a given quantity of sulfuric acid. 'not feasible.

An object of the present invention is to pro- The process of the present invention possesses duce a maximuih of ethyl alcohol from a given a further advantage in that more diethyl sulfate quantity of sulfuric acid. can be recovered in this way than can be obtained In the reaction of ethylene and sulfuric acid by diluting the acid product, diluting with water the initial product is ethyl hydrogen sulfate or and mechanically removing the diethyl sulfate. ethyl sulfuric acid. However, diethyl sulfate is This will be understood from .the fact that when also formed, and the acid product contains dithe undiluted acid reaction product is heated and ethyl sulfate, ethyl sulfuric acid and sulfuric acid distilled under vacuum, the diethyl sulfate preswhen only one mol. of ethylene has been absorbed ent dlstills from the mixture, and s this 15 in one 'mol. of sulfuric acid. As more ethylene moved from the mixture, more is formed from is combined in the acid reaction mixture, the the ethyl hydrogen sulfate, according to the equi- 20 proportion of diethyl sulfate increases. When librium:

using ordinary concentrated sulfuric acid, 66 B., r

and absorbing the ethylene under pressures of 2 etfiyl hydrogen sulfatesthethyl s l f fi acid 250 lbs. or more per square inch at about 70 to C" the reaction. rate fiatisfactory until It is, of course, not economically possible to con- 25 abbut L5 mols. orethylene to of vert all of the ethyl hydrogen sulfate to diethyl furic acid has been absorbed. Various factors sulfate m this manner the P e operate against obtaining the theoretical limit eratton of sulfuric t this way makes t of two mols f ethylene to bne of sulfuric acid, residual acid mixture more suitable for reaction or pure diethyl sulfate. Thus, when sulfuric with additional ethylene?" 30 I acid containing water is employed, such as -85 The process-tot the present invention has to 96% H2504, the yield of diethyl sulfate is lowfurther f that by hydmtysts the er as the proportion of water" present is greater. distillei methyl :tulfate and distillation of the Also, when nearly anhydrous or 100% sulfuric n h a' (mute acid is producedtfree ft'om acid is employed, side reactions and carbonizacarbon and which can berewoncentmteti 35 tion may occur, decreasing the yields and interdue to presente of carbon" 1 fering with the recovery of the sulfuric acid. The residual acld Preferably supplemented Also, when diethyl and monoethyl sulfates are with 96 to 100% sulfuric, "4 m order that the hydrolyzed together, with water, a substantial proportion of water in the reactitm mixture Proportion of ethyl ether is formed. will t progltesslvely increase" This residual The present invention relates to a process of acid wlt'h addmons of fresh acid used absorbing ethylene in sulfuric acidunder approover" and over again In gg tmtiauy priate conditions of temperature, acid concenti a- 96% g g :38 i; to g tion and pressure, until a substantial proportion e y me un er prgssure amount of blackening or carbon zation occurs. It is accordingly preferable to minimize the carvrruxture is then subjected to reduced pressure bomzafion by operating at somewhat lower heated to effect distillation of n peratures than are otherwise to be preferred, and fate from the Immune, h diethyl sulfate then accordingly in the practice of the present invenbeing hydrolyzed by Water dilute acid to tion'it is preferred to carry out the reaction with 50 ethyl alcohol. The residual acid mixture may ethylene u pressure t 70 to 30 I the be P y hydrolized t0 ethyl 81601101 When the carbonaceous material has accumuwithout forming ether or may be re-saturated lated in the residual recycled acid reaction mix with ethylene, again heated under reduced pres ture to an extent that may cause operating dif:

sure to recover diethyl sulfate, and the process .flculties, the mixture may be diluted with water, 55'- the sulfuric esters hydrolyzed in the usual manner and the alcohol distilled. A large proportion of the carbonaceous matter in the diluted acid separates out in a form which can be mechanically removed, as by filtering through a sand filter, before re-concentrating the acid. The concentration of carbonaceous matter in this way, and mechanical removal of large proportions of it before re-concentrating the acid, constitutes a further advantage of the present invention.

It was found further that due to decrease in the absorption or reaction rate of the ethylene it is not advantageous to continue passing ethylene into the acid after about 1.5 mols of ethylene are absorbed per one mol. of sulfuric acid, when using initially acid of not over 96% H2804 and a temperature of about With acid of 98 to H2804 the absorption of ethylene can be carried somewhat further, up to about 1.75 to 1.80 mols of ethylene to one of sulfuric acid, to, form larger proportions of diethyl sulfate.

When the reaction with the ethylene, or gas containing ethylene, has progressed until the absorption of the ethylene is markedly retarded, the acid reaction mixture is removed from the absorption apparatus and preferably, without cooling or storage, is transferred to a vacuumstill in which-it is subjected to further heating under reduced pressure and the diethyl sulfate is distilled from the mixture. The ethyl hydrogen sulfate has a solvent action for the diethyl sulfate and it is necessary to employ somewhat higher temperatures or lower pressures, or both, than when distilling pure diethyl sulfate. The diethyl sulfate and ethyl sulfuric acid are miscible in all proportions. Although the decomposition of diethyl sulfate is not very rapid below 150,

it is preferred to maintain the temperature of the still, or contentsof the still, at not over 0., and to maintain an absolute pressure of 20 mm. of mercury, or lower, on the vapors. Under these conditions most of the diethyl sulfate distills and is condensed in a suitable condenser and collected in an appropriate receiver. The still employed for this purpose may be'a lead lined still or a still made of acid resistant material such as acid resistant alloys, provided with a jacket, or internal heating coils, for supplying heat by steam, hot oil and the like, and operating on the batch principle. However, to minimize decomposition during the distillation process, it is preferred to pass the acid reaction mixture containing diethyl sulfate through a still of the column or fllm evaporator type, in which small quantities of the acid reaction mixture are heated for only a relatively brief interval of time, under reduced pressure. This also permits heating the material to a. higher temperature with less 'decomposition than in the caseof the more pro longed batch method of distillation. 4

The method of carrying out the process of the present invention is shown diagrammatically in the accompanying drawing. Sulfuric acid, which may be preheated if desired, is introduced into the blow case I from which it flows by the line 2 steam orother heating, medium.

-When the hydrolysis of the diethyl sulfate has been practically completed, the hydrolyzed and the control valve 3 to the absorber '4. The absorber 4 is constructed of acid-resistant ma terial and the temperature of the acid reaction mixture is maintained at the desired operating temperature by heating.or coolingco'ils, not

through the line I, and a suitable control valve 8. The acid reaction mixture containing mainly diethyl sulfate and ethyl hydrogen sulfateis removed from the absorber 4 by the line 9 and a release valve l0 and introduced into the tower or chamber II where the gases, dissolved in the acid liquid, are released and led out through the pipe l2. The acid reaction mixture is then withdrawn through the pipe l3 and pumped by the pump l4 to the vacuum still IS. The vacuum still is heated by the heating coils l6 or by a steam jacket or other suitable means. Instead of the tower type of still, a pipe still or film evaporator type of apparatus or other type of still suitable for distillation under reduced pressure and constructed of acid-resistant material, may be employed. The vapors containing diethyl sulfate are removed through the pipe I1 and passed to the condenser IS. The residual acid reaction. mixture, after partially or completely removing the diethyl sulfate, is removed from the still [5 by the line l9 and the pump 20, and may then be passed through the valve 2| and the pipe 22 and valve 23 back to the ethylene absorber 4; or the residual acid mixture from the still l5 may be passed through the pipe 24 and the valve 25. to the hydrolyzer 26. .Although there are advantages in separately hydrolyzing the, residual acid reaction mixture, which has been freed from diethyl sulfate, the maximum acid economy is realized by returning the residual acid reaction mixture from the still I5 to the absorber 4.

The residual acid reaction mixture, substantially free from diethyl sulfate, is mixed with water, introduced through the pipe 21 and hydrolyzed in the vessel 26, converting most of the ethyl sulfuric acid to alcohol and free sulfuric acid. The hydrolysis and distillation can be carried out simultaneously, suflicient time being allowed for substantially complete hydrolysis, but the procedure shown in the accompanying diagrammatic drawing, in which hydrolysis of the ethyl sulfuric acid is separately carried out, is satisfactory. Dilution with water equivalent to 35 parts of sulfuric acid upon final hydrolysis, to 65 parts by water, and a hydrolyzing temperature of 60 to 80 C. is preferable. The hydrolyzed acid product may be removed from the hydrolyzer 26 by the pipe 28 and the valve 29, and pumped by a suitable pump 30 to a still 3|.

The diethyl sulfate condensed in the condenser I8 is passed into the receiver 32 which is connected by the pipe 33 to a suitable vacuum pump, not shown. The still I5, condenser I II and receiver 32 are in free communication, the reduced' pressure 'being maintained on all three vessels.

material may be withdrawn through the pipe 39 and the valve 40 and passed by the pump 30 to the still 2| 'where the alcohol is removed by distillation and condensed in a suitable condenser,

not shown.

This process may also be used in the manufacture of isopropyl alcohol in that the separation of di-isopropyl sulfate may also be made by distillation at reduced pressure whereby the formation of ether is reduced and larger yields of alcohols are obtained.

The foregoing description is merely illustrative and various changes and alternative arrangements may be made within the scope of the appended claims in which it is my intention to claim all inherent novelty in the invention as broadly as the prior art permits. e

I claim:

1. In the manufacture of alcohols from olefines, the process which comprises absorbingat a pressure of at least 250 pounds per square inch an olefine of the group consisting of ethylene and propylene in sulfuric acid maintained at a temperature of about 70 to about 100 C. in order to obtain a dialkyl sulfate, subjecting the sulfuric acid containing the dialkyl sulfate to distillation under reduced pressure to separate the dialkyl sulfate and hydrolyzing the separated dialkyl sulfate to obtain an alcohol.

2. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds'per square inch ethylene in sulfuric acid maintained at a temperature of about to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate and hydrolyzing the separated diethyl sulfate to form ethyl alcohol.

'3. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch the ethylene in sulfuric acid maintained at a temperature of about 70 to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate, absorbing ethylene in the residual sulfuric at a pressure of at least 250 pounds per square inch ethylene in sulfuric acid maintained at a temperature of about 701 to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate and separately hydrolyzing the separated diethyl sulfate and the residual sulfuric acid to form ethyl alcohol.

6. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing 4 at a pressure of at least 250 pounds per square inch ethylene in sulfuric acid of 95 to 96% strength maintained at a temperature of about 70 to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate and hydrolyzing the separated diethyl sulfate and the residual sulfuric acid to form ethyl alcohol.

7. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch ethylene in sulfuric acid maintained at a temperature of about 70 to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the' diethyl sulfate to distillation under an absolute pressure not over 30 mm. of mercury to separate diethyl sulfate and hydrolyzing the separated diethyl sulfate to form ethyl alcohol.

8. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch ethylene in sulfuric acid at a temperature of about 70 to C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate and hydrolyzing the separated diethyl sulfate to form ethyl alcohol.

9. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch about 1 mols of ethylene in sulfuric acid of to 96% strength maintained at a temperaform ethyl alcohol.

10. In the manufacture of ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch about 1 mols of ethylene in sulfuric acid of 90 to strength maintained at a temperature of about 70 to about 100 C. to form a substantial proportion of diethyl sulfate, subjecting the sulfuric acid containing the diethyl sulfate to distillation under a pressure lower than atmospheric pressure to separate the diethyl sulfate and hydrolyzing the separated diethyl sulfate to form ethyl alcohol.

11. In the manufactureof ethyl alcohol from ethylene, the process which comprises absorbing at a pressure of at least 250 pounds per square inch 1.75 to 1.8 mols of ethylene in sulfuric acid of 98 to 100% strength to form a substantial proportion of diethyl sulfate, subjecting the sulfuric 

